Casuarina equisetifolia

Casuarina equisetifolia is a tree native to Australia and Southeast Asia particularly suited to coastal areas, due to its resistance to wind and sea spray. With extremely rapid growth, it forms a tall, slender tree, with a grey trunk, and fine branches, which from a distance resemble certain Pines. Not very hardy, it only tolerates winters in the warmest areas. Capable of growing in most well-drained soils, even sandy soils, it proves very resistant to drought once well-rooted. Its architectural silhouette is truly aesthetic in southern gardens.

The Casuarina belongs to the fairly obscure family of the Casuarinaceae, which only includes 4 genera of trees or bushes with a Horsetail-like appearance (scientific name: Equisetum). C. equisetifolia is a medium to large-sized tree with very fine foliage resembling Horsetail stems. It is native to Southeast Asia (Malaysia, Vietnam, Thailand, the Philippines...), the Maldives, and Australia, where it often grows by the seaside, on beaches. Despite its very rapid growth, it forms a very hard wood, called ironwood, used as firewood or charcoal by local populations. In these countries, it can reach heights of up to 35 m (114 ft 10 in).

In our climates the height reaches between 12 and 18 m, mainly because it always runs the risk of freezing during exceptional winters. However, this should not discourage planting it, as its growth is exceptionally fast. Regularly watered at the beginning, it can grow up to 1.50 m (4 ft 11 in) per year during the first 3 or 4 years of planting! It forms a trunk with a dark grey, decorative bark, which then divides into a few large main branches carrying the typical smaller branches. These branches are made up of extremely thin segments (only 2 mm (0.1 in) thick and up to 9 mm (0.4 in) long), nested within each other. The leaves are completely shrunk, reduced to simple tiny scales (1 mm (0 in)), grouped in whorls of 4 at each branch joint. What is thought to be the foliage is actually made up of the tree's stems. Their fineness gives it a very light appearance, reminiscent of certain conifers, hence its common name of Australian Pine.
This physiological characteristic gives it a truly elegant habit, with an erect yet semi-weeping aspect, as the flexible branches cascade downwards at their tips. It is generally twice as tall as it is wide, but its appearance can be quite varied. The branches take on a somewhat dull, greyish green, but this does not detract from the overall beauty of the plant. Its architectural silhouette is recognizable and instantly brings an exotic touch to the garden. The spring flowering is relatively insignificant, consisting of male flowers that turn cream to brown, and reddish female flowers. The brown-green fruits have the shape of small pine cones and contain small winged seeds, dispersed by the wind.
The Australian Pine grows in soils of various chemical compositions, its roots contain nodules capable of fixing nitrogen from the air thanks to bacteria (like Legumes), making it a pioneer plant. It is also capable of growing in sand close to the ocean, trapping salt in its "leaves" which then fall to the ground. They then form a litter that prevents the growth of other plants. Capable of growing in very poor sandy soil, it also withstands wind and sea spray. It can tolerate very severe pruning. In conclusion, it only dislikes frost, which can cause its death from -5°C (23 °F) to -7°C (19.4 °F).

Symbolic of tropical beaches, the Casuarina leaves its typical silhouette on the landscapes of warm countries. In warm gardens it can be associated with other tender plants to create an incredibly exotic scene. The Syagrus romanzoffiana, a palm tree resembling a coconut palm with its slender and gracefully curved fronds, will perfectly set the ambiance. The pink pompoms of the Calliandra surinamensis, which bloom all summer will also beautifully accompany these evocative plants.